This invention relates to a wet shaving razor comprising a cartridge that includes a shaving blade with a cutting edge which is moved across the surface of the skin being shaved by means of an adjoining handle. Conventional safety razors have a blade unit connected to a handle for a pivotal movement about pivotal axis which is substantially parallel to the blade or the blade edge. For example, U.S. Pat. Nos. 7,197,825 and 5,787,586 disclose such a razor having a blade unit capable of a pivotal movement about a pivot axis substantially parallel to the blade(s). The pivotal movement about the single axis provides some degree of conformance with the skin allowing the blade unit to follow the skin contours of a user during shaving. Such safety razors have been successfully marketed for many years. However, the blade unit can fail to remain flat and often disengages from the skin during shaving due to the blade unit's limited ability to pivot about the single axis combined with the dexterity required to control and maneuver the razor handle. The combination of these deficiencies can affect the glide and overall comfort during shaving.
There have been various proposals for mounting a cartridge on a handle to enable movement of the cartridge during shaving with the aim of maintaining conformity of the skin contacting parts with the skin surface during shaving. For example, many razors currently marketed have cartridges which are pivotable about longitudinal axes extending parallel to the cutting edges of the elongate blades incorporated in the cartridges. There is an increasing need to provide a shaving consumer with a closer, more effective shave. Applicant has attempted to provide this in its commercially available Fusion® razor which incorporates a spring in its following system to bring about a reduced cartridge to skin angle, which has been found to lead to a better shave. Similarly, others have attempted to manipulate the biasing mechanisms of their commercial razors. For instance, US Patent Publication 2005/0241162 A1 discloses a biasing assembly for a wet shave razor wherein the assembly includes 1) an abutment surface defined by a cartridge and located on the underside of the cartridge and 2) a biasing member extending outwardly from the handle and having an end which when the cartridge is coupled to the handle is in sliding engagement between the neutral and fully-rotated positions. The biasing member exerts a variable torque against the abutment surface. The reference, however, focuses primarily on a low spring force to prevent the cartridge from lifting off of the skin and does not focus on the effect that the biasing member has on maintaining the cartridge flat relative to the skin during shaving strokes and corresponding shaving closeness.
In addition, current shaving razors 10 found on the market typically include handle configurations that are variations of an ‘L’ shape where the longitudinal axis 30 of the handle 14 is offset from the razor cartridge 12 such that it intersects the cutting plane 122 behind the cartridge 12 as shown in FIG. 1. This configuration has the effect of pushing the razor cartridge 12 through the shaving stroke which can make it difficult to maneuver and can require a steady hand to steer the razor cartridge 12. In addition, the shaving razors have an axis of roll 36 (interchangeably referred to hereinafter as axis of roll 36 and handle roll axis 36) that extends between the free end of the handle 14 and a point on the cartridge where the forces are balanced. The axis of roll 36 is the line about which the razors spin in the direction shown in FIG. 1 when in a user's hand. For the L-shape configuration shown, this arrangement has a shortcoming. Since the handle longitudinal axis 30 extends above the axis of roll 36, instability is introduced during shaving, similar to a top heavy scenario that a user must compensate for when handling the razor. Hence, additional effort is required by the user to maintain stability of the razor during shaving.
In pursuit of an improved shaving product, there is a need for a shaving razor that can maintain the blade unit of a razor cartridge flat against the skin throughout a shaving stroke. Particularly there is a need for a shaving razor having a biasing member producing a progressively increasing return torque on a cartridge forcing the cartridge into contact with the skin throughout the shaving stroke. In addition, there is a need for a handle geometry that provides the user with improved control while shaving.